Inductive Kickback

[MileHigh]

Hi Tinman

There is really no sense for voltage to change polarity while the field is collapsing. Voltage and current have a strict relation between the two. Current always flow from higher voltage potential to a lower one and never the opposite even momentarily.

That is not true.  Suppose that you have two batteries that have a common ground.  One battery is +1 volt and the other battery is +2 volts.

What will happen if you connect a 1-ohm resistor between the two batteries?

The answer is that one amp of current will flow into the +1 volt battery.  So in this example, current is flowing in the "opposite" direction through the +1 volt battery.

[Jeg]

That is not true.  Suppose that you have two batteries that have a common ground.  One battery is +1 volt and the other battery is +2 volts.

What will happen if you connect a 1-ohm resistor between the two batteries?

The answer is that one amp of current will flow into the +1 volt battery.  So in this example, current is flowing in the "opposite" direction through the +1 volt battery.

Hi MH.
I said the same. Current flows from higher to lower potential always.

Ps. Ok MH I got it. Thanks.
  Inductor is now a power source itself, so yes Tinman is right. It changes voltage polarity but current flows the same direction inside the inductor. This is true.

[synchro1]

The voltage across the inductor invert's,but the current continues to flow in the same direction. The energy from the collapsing magnetic field is not new energy,it is stored energy from the initial input energy.

@Tinman,

Everything is everything!

[Magluvin]

From what i have found in the past is that the output of the coil when input is taken away doesnt necessarily have to be a spike.  It depends on the load it is sent to.
Like putting a diode across a relay coil to recirculate the bemf, the the field collapse is slower than with a higher ohm load. Most relays are high ohm already so it does drop off very fast. But a very low ohm winding with high induction should slope while diminishing through the diode rather than a quick spike reaction of a higher ohm coil.

I have coils that I had shown in Lucs thread that are .5ohm 2mh.  The bemf from those coils will heat up a 5w 5 ohm resistor that you cant touch when hot. And its not due to quick spikes.


Mags

[verpies]

When the current source to an inductor is interrupted, the current will continue to flow through the inductor in the same direction,but the voltage across that inductor will invert.

I agree.

I would add though, that the cause of current flow through an inductor can be:
- an external current source,
- an external voltage source,
- an external magnetic flux source,
- the inductor itself, since a current flowing through an ideal shorted inductor will flow forever.